Light sensitive tube



Jan. 10, V, K zwO LIGHT SENSITIVE TUBE Filed March 5. 1950 INVENTORVladimir K. Zwarykin ATTORNEY Patented Jan. 10, 1933 UNITED STATESPATENT OFFICE 4 HOUSE ELECTRIC A; IANUFACTURING COMPANY, A CORPORATIONOF PENNSW VAN IA LIGHT smsrrrvn roan Application filed Kai-oh 5,

This invention relates to a light sensitive device and especially to acomposite photo tube device.

' An object of the invention is to provide a composite light sensitivedevice capable of replacing a plurality of light sensitive devices.

Another object is to provide a more uniform structure of light sensitivedevices where a plurality of light sensitive elements are required andalso to diminish the capacity and leakage in the connecting leads tothese elements.

In certain systems, it is necessary to employ a plurality of lightsensitive surfaces in order to cover more than one spot on a surface atthe same time. Such a system maybe, for example, that described in mycopen mg application, Serial No. 199,392, for inspection devices, filedJune 16, 1927. It has hitherto been the custom in such a system toemploy a plurality of individual photo tubes. Unless such photo tubeswere purchased from a very reliable and careful manufacturer, such tubeswere not apt to be uniform in. their characteristics. Furthermore, theplurality of connecting leads to the various tubes were apt to produceboth a large capacity and also a leakage in the connecting leads.Accordingly, it is an object of my invention to provide a compositelight sensitive device or hoto tube that shall have a plurality of ightsensitive surfaces insulated from one another to replace the pluralityof individual photo tubes heretofore used. In forming such a device, theindividual surfaces may be made uniform within the device and the ca-1830. Serial No. 433,288.

velope or container 10 having at one end the glass seal or press 11.From this glass seal or press 11 extends a pro'ection or supportingelement preferably also of glass 12 extending for a considerable lengthof the tube. This g as projection 12 has preferably a plurality oflinearly extending sockets 13 and 14 which in the preferred from arealternately spaced or staggered on each side of the glass projection 12.

A plurality of light sensitive surfaces are preferably supported fromthe sockets in the manner disclosed in the drawing to keep the surfacesin place and insulated from each other preferably. A supporting wire 15is sealed into each glass socket and extends downward and is then bentat right angles parallel to the original socket, and is then secured inany preferred manner to the back of the light sensitive surface orelectrode 16. It is preferred to have this light sensitive surface orelectrode 16 in the shape of a slight- 1y obtuse angle as disclosed inthe drawing. It is also preferred to have the upper part of the upperleg of this electrode supported from a socket on each side of the glassprojection 12. A plurality of these electrodes 16 of any number desiredmay be supported along the glass projection 12 by means of the socketsand wires extending along the glass projection. It will be noted thatthe glass 'suplport 12 insulates the electrodes from one anot are spacedslightly from one another.

A connection 20 extends into the tube at the place 21 and is connectedto an electrode 22 that preferably acts only as an anode. Anotherconnection 23 preferably passes through the press 11 and extends to thefarther end 24 of the glass projection 12. This connection 23 ispreferably connected to the last light sensitive electrode b theconnection 25. For simplicity in manu acture, a disc 26 is preferablyfastened to the end of the glass projection and has on it one or moreamounts of caesium 27.

A preferred method of making the electrodes sensitive to light is asfollows. One surface of the electrode is coated with silver. Thissurface, of course, is the inner one with er and furthermore theelectrodes one leg slantingly facing the side of the tube.

\ This surface is oxidized, preferably by introducing a small amount ofoxygen to the tube and placing an electrode connected to a highfrequency current along the surfaces to discharge evenly thereto. Thisoxygen and electrode are then removed and the caesium is then flashed inany well known manner, so that the caesium will deposit upon the silveroxide surface of the electrodes. The tube is scaled up. The firstelectrode 22 does not have to be coated as it is connected to thepositive terminal 20 of the tube andacts merely as an anode.

The tube is formed, therefore, with a plu rality of electrodes spacedlinearly slig tly from one another and also insulated from one another.If light is directed upon the caesium surface 17 of these electrodes, itwill cause the caesium to be activated, so that a current applied acrossthe exterior connection 20, 23 of the tube will pass through the tubeprovided all the tubes are illuminated. The caesium will send offelectrons to the back or uncoated surface 18 of the adjacent electrodewith the result that the current will pass from the back of oneelectrode acting as an anode to the caesium coated surface of theadjacent electrode acting as a cathode. In other words, each electrodeacts as a cathode on its light sensitive surface and as an anode on itsuncoated surface. Accordingly, a current source connected to theconnections 20 and 23 will enter the first electrode 22 and pass fromthe back or anode, of said electrode to the light sensitive surface ofthe next electrode, provided such an electrode is illumined or madesensitive. The extension of one leg of the electrodes towards theadjacent inner surface of the tube prevents the electrons from skippingby any electrode and going to the next electrode.

If any one of these electrodes, however, is not illumined or madesensitive, it will not pass electrons from its light sensitive surfaceto the adjacent electrode and, accordingly, the conducting path throughthe tube will be broken and the entire tube will he non-conducting. Inother words, the failure of any electrode to be conducting will make theentire tube non-conducting. The first electrode.

22 however is not a light sensitive electrode due to its position in theseries and accordingly any description of the other electrodes is notintended to apply to electrode 22 which is only an anode.

This type of device is of special advantage in systems like my priorapplication hitherto referred to, Serial No. 199,392, in which theimperfection at any place in a surface requires such surface to beautomatically removed from the manufacturing process. The means forremoving such a surface may be such as that described in my copendingapplication just referred to or may be of any other arrangement, as thespecific means in connection with the tube just described is not withinthe scope of this invention.

Accordingly, there has been described a composite light sensitive deviceor photo tube containing a plurality of light sensitive surfaces thatwill replace the lurality of individual photo tubes hereto ore used invarious systems. Such a composite photo tube can be formed with moreuniform light sensitive surfaces and will also reduce the capacity andleakage due to the multiplicity of connecting leads in systems having aplurality of individual photo tubes.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that any modifications thereof are possible.My invention therefore, is not to be restricted except insofar as isnecessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. A light sensitive device comprising an evacuated container having aseries of aligned elements and an anode therein, each of said elements,having an anode surface and a photo-sensitive surface.

2. A light sensitive device comprising a supporting element, a series ofaligned electrodes and an anode carried thereby, each of said electrodesbeing insulated from the ad acent electrodes and being provided with alight sensitive layer on one side, whereby a conductive path may beestablished serially includlng said electrodes and the space betweenadjacent electrodes when the entire assembly is exposed to light.

3. light sensitive device comprising a contamer, a supporting element insaid contamer, a series of light sensitive electrodes supported by saidelement, a connection from one only of said light sensitive electrodesto the exterior of'said container, an electrode adapted to act as ananode for at least one of said light sensitive electrodes and aconnectlon from said electrode to the exterior of said container.

In testimony whereof, I have hereunto subscribed my name this 13th-dayof February 1930. VLADIMIR K. ZWORYKIN.

